1. Field of the Invention
The invention relates to an adjustment fitting, in particular for a motor vehicle seat, having a first fitting part, having a second fitting part that is rotationally adjustable relative to the first fitting part about an axis of rotation, wherein the first fitting part has associated with it an outer wheel with internal teeth, in which wheel is inserted eccentrically to the axis of rotation, in the manner of a wobble mechanism, an inner wheel with external teeth that is associated with the second fitting part, and wherein the inner wheel forms a receiving space that is eccentric to the axis of rotation, having an eccentric cam rotatably inserted in the eccentric receiving space, and having a drive shaft for driving the eccentric cam.
2. Description of the Background Art
An adjustment fitting of this nature is known, for example, from DE 100 21 403 C2, DE 31 30 315 C2 and DE 28 34 529 C2, which corresponds to U.S. Pat. No. 4,322,112. In these fittings, the first fitting part and the second fitting part are connected in the manner of a wobble mechanism, wherein the inner wheel rolls with its external teeth along the internal teeth of the outer wheel with a wobbling motion when the eccentric cam is driven. The number of teeth in the external teeth is smaller than the number of teeth in the internal teeth. One full rotation of the eccentric cam results in a rotation of the inner wheel relative to the outer wheel by the difference in tooth count. An adjustment fitting with wobble mechanism has become established in the automotive industry for adjusting the backrest relative to the seat base of a motor vehicle seat. A wobble mechanism can be implemented with relatively few mechanical parts, and permits flat construction together with a transmission ratio desirable for adjustment.
In the final assembled state, the fitting parts, or the inner and outer wheel of such an adjustment fitting, are held together in the axial direction. An extremely wide variety of retaining means are known from the prior art for this purpose. If the axial play between the fitting parts is too great, the result is undesirable rattling noises, which the vehicle occupant may potentially find worrisome, or at the very least perceive as unpleasant. On the other hand, if the axial play between the fitting parts is too small, an unnecessarily high frictional force has to be overcome in order to adjust the fitting.
Known from the aforementioned DE 100 21 403 C2 for holding the two fitting parts together axially is a retention ring overlapping the two fitting parts that is attached in a rotationally fixed manner to at least one of the fitting parts by means of a polygonal interlock.
According to DE 10 105 282 B4, which corresponds to U.S. Pat. No. 6,799,806, the fitting parts of an adjustment fitting are held together axially by a retaining ring, wherein a fitting part is pressed into the retaining ring. This is intended to permit easier assembly. It is additionally proposed therein to design the retaining ring with an internal step, with the fitting part being pressed in up to said step.
From DE 31 30 315 C2, it is known to use a plate washer, which is permanently attached to one fitting part, for axially holding together the two fitting parts of an adjustment fitting. In this solution, the edge of the washer constitutes internal teeth that mesh with overhanging external teeth of the inner wheel. To hold the fitting parts together axially, the plate washer is interlocked with a retaining element that is pressed into slots in the other fitting part and is attached to this fitting part in a position with no play.
Finally, DE 28 34 529 C2 discloses a bearing plate holding the fitting parts of an adjustment fitting together axially, which has lateral bent portions that laterally overlap the two fitting parts. During assembly, the fitting parts are pressed together with no play, and the outer fitting part is permanently attached to the lateral bent portions in this position.